Jest transformIgnorePatterns not working

Question

I have spent a long time looking at other questions about this and looking at other projects on Github but none of the answers seem to work for me.

I am loading a third party library in my project, and when running Jest tests I get the error

export default portalCommunication;
^^^^^^

SyntaxError: Unexpected token export

> 1 | import portalCommunication from 'mathletics-portal-communication-service';

I have tried updating my Jest config in many ways to get it to transpile this library but I always get the same error.

This is my current jest.config.js file:

module.exports = {
    moduleNameMapper: {
        '\\.(css|scss)$': 'identity-obj-proxy',
        '\\.svg$': '<rootDir>/test/mocks/svg-mock.js'
    },
    setupFiles: ['./test/test-setup.js'],
    transformIgnorePatterns: [
        '<rootDir>/node_modules/(?!mathletics-portal-communication-service)'
    ]
};

I have also tried adding the transform property to run babel-jest against this mathletics-portal-communication-service directory.

Please help!

My project has babel set up and working fine, is there something special I would need to do for Jest? I thought it used babel-jest automatically? — Heather Roberts, May 03 '18 at 23:33
See related [question](https://stackoverflow.com/a/75089099/8285811) — Akaisteph7, Jan 11 '23 at 21:20

score 55 · Answer 1 · edited Aug 19 '22 at 13:01

55

The transformIgnorePatterns didn't work for me until I changed my .babelrc to babel.config.js, like this:

module.exports = {
    "presets": [
        "@babel/preset-env"
    ]
};

as seen on this comment: https://github.com/facebook/jest/issues/6229#issuecomment-403539460

edited Aug 19 '22 at 13:01

Penny Liu

15,447
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answered Feb 12 '19 at 18:35

NJCodeMonkey

811
7
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5

Do you know if a `.babelrc` or `babel.config.js` file is absolutely necessary? I'm trying to get mine working with just a `transformIgnorePatterns` declaration in my `package.json` – Yorkshireman Oct 23 '19 at 16:46
1

Looking at the linked github issue, it seems like it won't work in the package.json either, but I haven't tried it. – NJCodeMonkey Oct 24 '19 at 22:02
7

This response is underrated!! I had been bumping my head for several hours until I saw this! Heck this should be in the docs! – Samuel Imolorhe Jan 09 '20 at 14:26
2

Weird that .babelrc doesn't work while babel.config,js does. – Alec Gerona Jul 01 '20 at 04:25
thank you, you save my time! – Chaolong Liao Dec 24 '21 at 12:19
is there an issue with making the filename change? I mean, will this fix tests but potentially break something else? – Gabrielle Sep 14 '22 at 17:18
It took my the whole day to fix this error, installing this babel package and adding the babel.config.js solved it for me – Warwick Nov 18 '22 at 15:57

score 9 · Answer 2 · answered Sep 03 '21 at 14:37

9

Another team at my org added some common module. This was not transpiled and so the issue.

I followed this: https://babeljs.io/docs/en/configuration#whats-your-use-case

Converted my .babelrc to babel.config.json
in jest config added this: transformIgnorePatterns: ['/node_modules/(?!(@companyName)/).*/'],

This solved my problem.

answered Sep 03 '21 at 14:37

Rohan Bagchi

649
10
17

I saw someone say to add this to package.json.. uhh. Thank you so much! – Akaisteph7 Jan 11 '23 at 21:02

score 6 · Answer 3 · answered May 04 '18 at 04:53

As a workaround for now I have changed my config to use the moduleNameMapper option to load a mock class for that library instead. I would have preferred to use transformIgnorePatterns instead so would still appreciate any ideas.

New config:

module.exports = {
    moduleNameMapper: {
        '\\.(css|scss)$': 'identity-obj-proxy',
        '\\.svg$': '<rootDir>/test/mocks/svg-mock.js',
        'mathletics-portal-communication-service': '<rootDir>/test/mocks/mathletics-portal-communication-service-mock.js'
    },
    setupFiles: ['./test/test-setup.js']
};

This was the only thing that worked for my case as well – Rafael Steil Jun 24 '22 at 03:58 — Rafael Steil, Jun 24 '22 at 03:58

score 5 · Answer 4 · answered Jun 24 '21 at 22:49

5

Adding trailing slash fix this for me:

{
    // ...
    transformIgnorePatterns: [
        '<rootDir>/node_modules/(?!mathletics-portal-communication-service/)'
    ]
};

answered Jun 24 '21 at 22:49

Raz Luvaton

3,166
4
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score -4 · Answer 5 · answered Oct 25 '19 at 11:42

-4

It might be your use of rootDir. Try:

    "transformIgnorePatterns": [
      "node_modules/(?!(mathletics-portal-communication-service))"
    ]

answered Oct 25 '19 at 11:42

Yorkshireman

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Jest transformIgnorePatterns not working

5 Answers5

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